arch/arm/mach-rockchip/bootrom.c

   1 /**
   2  * Copyright (c) 2017 Google, Inc
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <common.h>
   8 #include <asm/arch/bootrom.h>
   9 #include <asm/arch/boot_mode.h>
  10 #include <asm/io.h>
  11 #include <asm/setjmp.h>
  12 #include <asm/system.h>
  13
  14 /*
  15  * Force the jmp_buf to the data-section, as .bss will not be valid
  16  * when save_boot_params is invoked.
  17  */
  18 static jmp_buf brom_ctx __section(".data");
  19
  20 static void _back_to_bootrom(enum rockchip_bootrom_cmd brom_cmd)
  21 {
  22         longjmp(brom_ctx, brom_cmd);
  23 }
  24
  25 void back_to_bootrom(enum rockchip_bootrom_cmd brom_cmd)
  26 {
  27 #if CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT)
  28         puts("Returning to boot ROM...\n");
  29 #endif
  30         _back_to_bootrom(brom_cmd);
  31 }
  32
  33 /*
  34  * we back to bootrom download mode if get a
  35  * BOOT_BROM_DOWNLOAD flag in boot mode register
  36  *
  37  * note: the boot mode register is configured by
  38  * application(next stage bootloader, kernel, etc),
  39  * and the bootrom never check this register, so we need
  40  * to check it and back to bootrom at very early bootstage(before
  41  * some basic configurations(such as interrupts) been
  42  * changed by TPL/SPL, as the bootrom download operation
  43  * relys on many default settings(such as interrupts) by
  44  * it's self.
  45  */
  46 static bool check_back_to_brom_dnl_flag(void)
  47 {
  48         u32 boot_mode;
  49
  50         if (CONFIG_ROCKCHIP_BOOT_MODE_REG) {
  51                 boot_mode = readl(CONFIG_ROCKCHIP_BOOT_MODE_REG);
  52                 if (boot_mode == BOOT_BROM_DOWNLOAD) {
  53                         writel(0, CONFIG_ROCKCHIP_BOOT_MODE_REG);
  54                         return true;
  55                 }
  56         }
  57
  58         return false;
  59 }
  60
  61 /*
  62  * All Rockchip BROM implementations enter with a valid stack-pointer,
  63  * so this can safely be implemented in C (providing a single
  64  * implementation both for ARMv7 and AArch64).
  65  */
  66 int save_boot_params(void)
  67 {
  68         int  ret = setjmp(brom_ctx);
  69
  70         switch (ret) {
  71         case 0:
  72                 if (check_back_to_brom_dnl_flag())
  73                         _back_to_bootrom(BROM_BOOT_ENTER_DNL);
  74                 /*
  75                  * This is the initial pass through this function
  76                  * (i.e. saving the context), setjmp just setup up the
  77                  * brom_ctx: transfer back into the startup-code at
  78                  * 'save_boot_params_ret' and let the compiler know
  79                  * that this will not return.
  80                  */
  81                 save_boot_params_ret();
  82                 while (true)
  83                         /* does not return */;
  84                 break;
  85
  86         case BROM_BOOT_NEXTSTAGE:
  87                 /*
  88                  * To instruct the BROM to boot the next stage, we
  89                  * need to return 0 to it: i.e. we need to rewrite
  90                  * the return code once more.
  91                  */
  92                 ret = 0;
  93                 break;
  94         case BROM_BOOT_ENTER_DNL:
  95                 /*
  96                  * A non-zero return value will instruct the BROM enter
  97                  * download mode.
  98                  */
  99                 ret = 1;
 100                 break;
 101         default:
 102 #if CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT)
 103                 puts("FATAL: unexpected command to back_to_bootrom()\n");
 104 #endif
 105                 hang();
 106         };
 107
 108         return ret;
 109 }